Micro-electro-mechanical systems (MEMS) can be used to create variable capacitors. Specifically, for example, as shown in FIG. 1a, a variable capacitor 1 can include a substrate 10 on which one or more fixed actuation electrodes 11 and one or more fixed capacitive electrodes 12 can be positioned. A movable component 20 can be suspended above substrate 10, movable component 20 being fixed with respect to substrate 10 at either end. Movable component 20 can include one or more movable actuation electrodes 21 and one or more movable capacitive electrodes 22. In this configuration, by controlling a potential difference between fixed actuation electrodes 11 and movable actuation electrodes 21, movable component 20 can be selectively moved toward or away from substrate 10. In this way, the capacitance between fixed capacitive electrode 12 and movable capacitive electrode 22 can be selectively varied. In some aspects, a layer of dielectric material can be deposited to cover the actuation electrode 11 and capactive electrode 12. The dielectric material can be planarized to provide a flat surface.
In some aspects, the substrate 10 and moveable component can be fixed by two anchor or support structures 23 on both ends as illustrated in FIG. 1B. In such configuration, however, applying a potential difference between fixed actuation electrodes 11 and movable actuation electrodes 21 can cause movable component 20 to flex toward substrate 10 unevenly, which can cause issues with charging in the actuator dielectric and wear. Furthermore, although it is desirable for movable capacitive electrode 22 to be able to move fully downward so that it can contact fixed capacitive electrode 12 to maximize the capacitance range, it can be undesirable for fixed actuation electrodes 11 and movable actuation electrodes 21 to get too close to one another since the electrodes can be subject to suddenly “snapping down” together after moving close enough to one another, as illustrated in FIG. 1B, and the device can suffer from dielectric damages and stiction caused by high electric fields between the actuator electrode for spacings that are too close.
Accordingly, it would be desirable for systems, devices, and methods for MEMS variable capacitors to more consistently bring its capacitor electrodes into close proximity while maintaining sufficient spacing of the adjacent actuator(s).